Tubular prostheses for transluminal implantation in body canals, for example urethra or ureters, for the purpose of repair or dilation are known. These prostheses, referred to herein as stents, may be generally tubular elements. Stents are self expanding or are balloon expandable radially within a lumen to open therethrough a passage, herein all types of stents will be referred to as expanding stents.
A typical self-expanding stent is disclosed in U.S. Pat. No. 4,655,771, Which stent has a radially and axially flexible, elastic tubular body of a predetermined diameter that is variable under axial movement of ends of the body relative to each other. That stent has of a plurality of individually rigid but flexible and elastic thread elements defining a radially self-expanding helix. The disclosure in U.S. Pat. No. 4,655,771 is made is a part hereof and incorporated herein by reference.
Placement of the stent according to U.S. Pat. No. 4,665,771 in a body vessel is achieved by a device having a piston to push the stent or a latch to hook the stent and push or pull it into position.
U.S. Pat. No. 4,990,151 has an instrument for the implantation or extraction of a stent. The instrument has a plurality of internally held spring members that are released by withdrawal of an over tube. The members thus engage the inside of the urethra to expand the lumen so the spring members can be advanced over the stent and caused to engage the outside thereof whereupon the over tube is positioned to keep the members engaged. While this instrument comes apart for sterilization and reuse, it is not adjustable for different size stents and was made to use for explantation.
U.S. Pat. No. 4,768,507 has a mandrel for carrying a spring helix inside a tube and is delivered by removing the tube so the helix spring can unwind and expand. It is shown as a disposable instrument.
U.S. Pat. No. 5,026,377 describes and claims in combination, a self-expanding braided stent as in '771 and an instrument for the deployment or retraction in a body canal of the stent. The instrument has an elongated tubular outer sleeve with proximal and distal ends, an elongated core in the sleeve is movable relative thereto so the core which is longer than the sleeve includes a grip member at or near its distal end. The grip member is on the core to: (I) releasably hold the self expanding stent within the outer sleeve,(ii) deploy the stent beyond the distal end of the outer sleeve when the outer sleeve is moved in a backward direction relative to the core and (iii) retract the stent back within said outer sleeve when the core is pulled in a backward direction relative to the outer sleeve.
European Patent Number EP 0 518 838 A1 has a transluminal implantation device for an implantation of substantially tubular, radially expandable stent. The device has a central tube or shaft surrounded by an outer tube axially displaceable relative said central tube or shaft, the radial dimensions of the tubes or tube and shaft forming an annular space therebetween for holding the stent in an unexpanded state. The held stent can be axial displaced from the outer tube relative to said central tube or shaft at a distal end thereof. There is an undercut groove forming a circumferential flange wherein the proximal end of the stent rests until release with rearward displacement of the outer tube.
It has now been found that a reusable deployment instrument for implanting a variety of stent designs and configurations may be needed to reduce the cost and expense of medical care. The need to sterilize and adjust the instrument has not been solved by the disposable deployment devices available. Moreover it is not a simple matter to revise such disposable tools to be used for more than one time. Manufactures of those disposable devices strive to make such tools difficult or impossible to reuse.
This invention relates to a reusable instrument for the placement of a stent in a body canal, and means for positioning and releasing the stent.